packet_to_flow_match: use OFPVID_PRESENT

The spec requires OFPVID_PRESENT (the CFI bit) to be included in the vlan_vid
value if matching on a vlan id.
diff --git a/src/python/oftest/parse.py b/src/python/oftest/parse.py
index 8c98c91..7963c0c 100644
--- a/src/python/oftest/parse.py
+++ b/src/python/oftest/parse.py
@@ -196,7 +196,7 @@
         if type(layer.payload) == scapy.Dot1Q:
             layer = layer.payload
             match.oxm_list.append(ofp.oxm.eth_type(layer.type))
-            match.oxm_list.append(ofp.oxm.vlan_vid(layer.vlan))
+            match.oxm_list.append(ofp.oxm.vlan_vid(ofp.OFPVID_PRESENT|layer.vlan))
             match.oxm_list.append(ofp.oxm.vlan_pcp(layer.prio))
         else:
             match.oxm_list.append(ofp.oxm.eth_type(layer.type))